Two piece ammunition round

ABSTRACT

A sabot and projectile ammunition round having a mismatched load transfer interface to eliminate interface stripping failures. The pitch of the sabot grooves, or threads are slightly larger than the pitch of the mating projectile grooves or threads. The initial contact only exists between the forwardmost tooth of the sabot and the projectile. When fired the powder pressure force causes shortening of the sabot grooves and lengthening of the projectile grooves. Thus the power pressure load is transferred from the sabot to the projectile by successive loading of respective sabot and projectile teeth.

United States Patent [191 Kaplan et al.

[ TWO PIECE AMMUNITION ROUND [75] Inventors: Abner Kaplan, Palos Verdes;

William J. Dean, Hawthorne, both of Calif.

[73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC.

[22] Filed: June 28, 1973 [21] Appl. No.: 374,602

[52] 11.8. C1. 102/93 [51] Int. Cl. F421) 13/16, F42b 31/00 [58] Field of Search 102/93, 94, 49.1

[56] References Cited UNITED STATES PATENTS 1,475,578 11/1923 Hadfield et al. 102/93 2,638,051 5/1953 Critchfield.. 102/93 2,996,011 8/1961 Dunlap 102/93 3,262,391 7/1966 Shober 102/93 FOREIGN PATENTS OR APPLICATIONS 1/1967 Great Britain 102/49.1

[111 3,859,922 [451 Jan. 14, 1975 Primary Examiner-Samuel Feinbe rg Assistant Examiner-C. T. Jordan Attorney, Agent, or Firm-Edward J. Kelly; Herbert Berl; Charles R. Carter [57] ABSTRACT A sabot and projectile ammunition round having a mismatched load transfer interface to eliminate interface stripping failures. The pitch of the sabot grooves, or threads are slightly larger than the pitch of the mating projectile grooves or threads. The initial contact only exists between the forwardrnost tooth of the sabot and the projectile. When fired the powder pressure force causes shortening of the sabot grooves and lengthening of the projectile grooves. Thus the power pressure load is transferred from the sabot to the projectile by successive loading of respective sabot and projectile teeth.

2 Claims, 1 Drawing Figure TWO PIECE AMMUNITION ROUND BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION The present invention has overcome the above stated problem by mismatching the mating teeth of the sabot and the projectile. Upon firing of the ammunition round the invention causes the progressive closing of g the tooth gaps (front to rear) by relative straining of the sabot and projectile material.

This invention may be better understood from the following detailed description taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE shown is a schematic of the sabot-projectile interface.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference numeral indicates a gun barrel from which a two piece ammunition round is fired. The two piece round includes a projectile 12 and a surrounding sabot 14. Gaspressure 16 from a powder source (not shown) is used to fire the two piece round out of the barrel. Part of the propelling force is transferred from the sabot to the projectile by the tooth interface therebetween. The pitch of the sabot grooves 18 is made slightly larger than the pitch of the mating projectile grooves 20. Thus prior to the transferring of the full force to the projectile only the forwardmost tooth pairs 22, 24 of the sabot and projectile respectively are engaged and therefore capable of transferring load. All of the other tooth pairs have varying gaps from front to rear as shown at 26.

In operation gas pressure causes the progressive closing of the tooth gaps from front to rear by relative straining of the sabot and projectile material. The initial load increment applied to the aft surface of the sabot will cause the sabot material to compress up to the forward tooth where engagement with'the projectile already exists. This same force increment will produce a tensile stress and elongation in the projectile material. Under this initial load increment, due to the sabot compressive shortening and the projectile lengthening, the teeth gaps will tend to close. Depending on the initial tooth gaps, a given load increment will cause the second tooth pair to become engaged so that further load transfer would be accommmodated by two pairs of engaged teeth. This same process would then be repeated with each successive load increment causing the engagement of the next tooth pair until the aft most teeth are engaged. In this way, the load is forced initially forward and then is permitted to distribute progressively aft. By proper variation of tooth gapping (relative pitch) along the sabot, the load transfer can be made equal for each tooth and thereby the maximum shear load transfer capability of a given interface configuration can be achieved.

We claim:

1. A transfer means comprising; an interface for transferring a load radially from one member to a second member; said interface including teeth on said second member; said members having one tooth in load bearing engagement, each of said members having a groove pitch to separate said teeth, the groove pitch of said first member being slightly larger than the groove pitch of said second member so that the spacing between successive mating teeth progressively increases whereby the area of pressure surface contact is progressively increased by the compression of the sabot material and the elongation of the projectile material bringing successive teeth into load bearing engagement with each other.

2. A two piece ammunition round comprising; means for transferring a load radially from the first piece to the second piece; said means including teeth on said first piece and teeth on said second piece; said pieces having one tooth in load bearing engagement, each of said pieces having a groove pitch to separate said teeth, the groove pitch of said first piece being slightly larger than the groove pitch of said second piece so that the spacing between successive mating teeth progressively increases whereby the area of pressure surface contact is progressively increased by the compression of the sabot material and the elongation of the projectile material bringing successive teeth into load bearing engagement with each other. 

1. A transfer means comprising; an interface for transferring a load radially from one member to a second member; said interface including teeth on said second member; said members having one tooth in load bearing engagement, each of said members having a groove pitch to separate said teeth, the groove pitch of said first member being slightly larger than the groove pitch of said second member so that the spacing between successive mating teeth progressively increases whereby the area of pressure surface contact is progressively increased by the compression of the sabot material and the elongation of the projectile material bringing successive teeth into load bearing engagement with each other.
 2. A two piece ammunition round comprising; means for transferring a load radially from the first piece to the second piece; said means including teeth on said first piece and teeth on said second piece; said pieces having one tooth in load bearing engagement, each of said pieces having a groove pitch to separate said teeth, the groove pitch of said first piece being slightly larger than the groove pitch of said second piece so that the spacing between successive mating teeth progressively increases whereby the area of pressure surface contact is progressively increased by the compression of the sabot material and the elongation of the projectile material bringing successive teeth into load bearing engagement with each other. 